This invention relates to the diffusion of substances between two fluids via semi-permeable membranes and, more particularly, to an improved arrangement for interconnection of the membranes.
In such an arrangement, the membranes are arranged in a stack of at least two pairs of membranes, with a first fluid being conducted between the membranes in these pairs and a second fluid being conducted outside the same membranes. In prior art arrangements for the diffusion of substances between two fluids via semi-permeable membranes, providing channels between membranes arranged in pairs was brought about by clamping the membranes together at points or along certain lines within carefully defined areas. Most frequently relatively complicated spacing plates were used with a plurality of projections and channels arranged between them. Examples of such constructions are described for example in U.S. Pat. Nos. 3,411,630 and 3,516,548.
In a later construction which forms the subject of the U.S. Pat. No. 4,016,082, a similar grating of channels is produced instead by glueing, hot-sealing, etc. within a pattern of points, lines and/or small areas. This made it possible to simplify the spacing plates and to design them as simple frames, which required less precision in manufacture than the aforementioned complicated spacing plates.